9x20 Lathe Digital Read-Out (DRO)
Last updated on Tuesday, September 19, 2023 04:31:13 PM Mountain US Time Zone


9x20 Lathe DRO, DRO Wall Mount Bracket,
DPU-550 Daughterboard Upgrade,
Lathe Work Light

9x20 Lathe DRO

The lathe is at the upper limits of weight & size that I could
safely move down a hill & into my lower
-level walkout.

X-axis scale is mounted off the back of the carriage so there
is no interference with the tailstock. Both L-channel

mounts effectively protect the scales from impact, fluid & debris.
For my particular setup, the lathe is still the same

 distance from the wall as before the scale addition.
DRO is mounted onto wall. Its location positions the DRO

away from any cutting fluid spray. When the X-axis scale is
set to the diameter mode, its far left decimal is on.

The tachometer is indicating 637 RPM on the Z2 display. 
The auxiliary port must be first set to ON in setup, then

tachometer & SFM are activated using Functions 7 & 8, respectively.
Scales directions & polarities must be correctly defined in the
DRO setup for several of the functions to work properly.

DRO Wall Mount Bracket

The arm pivots at both ends. Concrete screws used as wall fasteners.
Since the mount is so rigid, there is no need to offset the bracket like that done
for the
Mill DRO. Plugged fastener access holes with black, 5/8" diameter,
 snap-in plastic caps. Cables are spiral wrapped for protection.
Adding a deep red filter enhances the LED display

The five LED indicators have circular (punched)
red filters, placed in the enclosure cover, too.

The DRO is plugged into a surge protector.

DPU-550 Daughterboard Upgrade

The DRO-350 has been
upgraded with the DPU-550 daughterboard &
overlay for enhanced capabilities.


OpenDRO User's Guide Rev 5 
OpenDRO Supplemental Guide 
OpenDRO Software Upload Manual 


Scales' directions & polarities must be
correctly defined in the DRO setup for

several of the functions to work properly. Refer to
page 38 of the Open DRO Supplemental Guide.

DPU-550 for the 9x20 lathe showing 146 RPM.
For the DPU-550, a 74LS14 Schmitt Trigger was
needed to make the tachometer work reliably.

Since any input can be displayed on any line, the RPM is
assigned to the middle line & Z1 to the bottom line.

The X-axis far left decimal is illuminated indicating it is in diameter
mode. Of the numerous features, some include:
fractional input, reverse Polish calculator, high-precision displays,
large storage & USB interface.

With the variable speed DC lathe motor modification,
I can now dial-in speed to display a specific SFM (e.g., 200)
which varies instantaneously with diameter changes.

Lathe Work Light

All cable plugs are held in place with a spot of hot glue.
Don't let any volatile liquids seep in behind the

DRO's overlay, it might damage the silkscreen. I accidentally
splashed mine with isopropyl alcohol while on

 the bench, causing damage. The overlay has since been replaced.
It pulled off but it left quite a bit of sticky

residue to remove since I had used the suggested (excellent)
3M Super 77 adhesive for mounting.

The newer upgraded overlay for the DPU-550 has double-sided
tape applied in the proper areas, only.

An upgraded display mount design allows better pivoting
positions & incorporates a cable tie strain relief.

Installed a galvanized steel extension plate to move
the light's magnetic base towards the back.

The plate is an electrical-box cover.

An upgraded task/machine work light
(USA) for the Jet 9x20 lathe setup.

It uses up to a 100W (maximum)
halogen or incandescent lamp.

Double-walled shade with a finned aluminum heat sink
keep it cool to the touch & extends switch life.

The lamp's head can be directed more
effectively than the previous light.

Discarded the magnetic base & bolted directly to the
cross-slide T-groove. The mount uses 6mm cap head

bolts with steel T-nuts. The original base bolts were
1/4-20 but the 6mm bolts used here fitted perfectly.

Now the lamp is very secure when moving the head
around & there is no magnet to attract metal swarf.

Made a steel bracket to extend the lamp base back
2-1/2-inches. The T fits into the cross slide table slot.

A heavy chamfer was filed to protect the
cord from being abraded by the edge.

All threads & bolts are M6-1. The top of the bracket &
the two set screws are below the table's surface.

The sturdy lamp mount was kept independent of the
transducer cover/bracket to isolate lamp adjustments.

9x20 Lathe DRO, DRO Wall Mount Bracket,
DPU-550 Daughterboard Upgrade,
Lathe Work Light